Observationally, the spectral energy distribution (SED) of blazars in a
\(\nu \) F\(_\nu \)  representation shows two broad distinctive peaks [1]}. The most widely accepted interpretation of the first bump of the SED is that it is due to synchrotron radiation of relativistic electrons
moving along the jet. Different models offer alternative solutions as to the origin of the second
spectral component, namely leptonic or hadronic. In the leptonic model, the
second peak is the result of inverse Compton (IC) scattering of low-energy
photons to high energies by the very same electrons that produce the
synchrotron peak. The up-scattered photons can be the synchrotron photons themselves [2]}, [3]} or ambient photons of different
origins [4]}. On the
other hand, hadronic models establish the origin of the second peak as
synchrotron emission from high-energy protons or photoproduction induced by
accelerated protons [5]}, [6]}, [7]}.
Blazars presenting the first peak in their SED at UV/X-ray energies
(\(\nu _{peak}^{S} > \)  10\(^{15}\)  Hz) are referred to as high-synchrotron peaked
blazars (HSPs). For intermediate-synchrotron peaked blazars (ISPs), the
synchrotron peak frequency lies at 10\(^{14}\)  Hz \(< \nu _{peak}^{S} <\)  10\(^{15}\) 
Hz. Those blazars presenting their synchrotron peak frequency at
\(\nu _{peak}^{S} < \)  10\(^{14}\)  Hz, between radio and optical wavelengths, are
known as low-synchrotron peaked blazars
[8]}. BL Lacs can belong to all these three
categories, while most FSRQs have been classified as LSPs.
